According to the National Survey on Drug Use and Health (2004), an estimated 76 million people worldwide have alcohol addiction, including harmful use and dependence. In the United States, the number of people with alcohol addiction is estimated at 10 million.
Many people who would like to quit use of abused agents cannot because they are addicted to one or more dependence-inducing components (e.g., alcohol, nicotine, morphine, cocaine, amphetamine, caffeine, methamphetamine, etc.). Moreover, treatment for substance abuse often involves transfer of dependence to an alternative, but also dependence-inducing agent. Even successful treatment often involves significant and unpleasant withdrawal symptoms.
For example, alcohol dependence constitutes one of the most serious public health problems worldwide. There are only three medications available for the treatment of alcohol dependence: disulfiram, acamprosate, and naltrexone. The opioid antagonist, naltrexone has demonstrated the most consistent effect in reducing alcohol consumption in the context of behavioral therapy (Anton et al., JAMA 2006, 295, 2003-17). Naltrexone has been shown to decrease ethanol consumption in numerous animal studies (Altshuler et al., Life Sci. 1980, 26, 679-88; Froehlich et al., Pharmacol. Biochem. Behav. 1990, 35, 385-90; Stromberg et al., Alcohol Clin. Exp. Res. 1998, 22, 2186-91; Stromberg et al., Alcohol 2001, 23, 109-16; Volpicelli et al., Life Sci. 1986, 38, 841-7) and clinical studies (Anton et al., J. Clin. Psychopharmacol. 2001, 21, 72-7; O'Malley et al., Arch. Gen. Psychiatry 1992, 49, 881-7; Oslin et al., Am. J. Geriatr. Psychiatry 1997, 5, 324-32; Volpicelli et al., Arch. Gen. Psychiatry 1992, 49, 876-80) and has been shown to be more effective in heavy or excessive drinkers (Pettinati et al., J. Clin. Psychopharmacol. 2006, 26, 610-25). However, not all patients respond to naltrexone and this is partly explained by genetic variations in the mu opioid receptor gene (Oslin et al., Addict. Biol. 2006, 11, 397-403). Furthermore, opioid receptor antagonists decrease both ethanol and sucrose intake in rodents (Beczkowska et al., Brain Res. 1992, 589, 291-301; Stromberg et al., Pharmacol. Biochem. Behav. 2002, 72, 483-90). Alcohol dependence is a complex disorder that will require the use of different therapeutic approaches to effectively treat the disease.
Clearly, there remains a need for improved therapies for alcohol abuse and dependency as well as for substance-related disorders in general.